In this episode of the Nico Misleh Podcast, Nico explains why the long-standing fear that testosterone replacement therapy (TRT) causes blood clots is outdated. He walks listeners through the science, the big studies, and practical advice for patients and providers. His message is clear. When looked at carefully, testosterone replacement therapy does not increase the risk of venous thromboembolism or related clotting events. Instead, the evidence suggests neutral or even protective effects when hormone levels are optimized.
What the Research Actually Shows
Nico points to large clinical studies as the main reason to drop the myth. He highlights the Traverse trial, a wide and well-designed study that tracked thousands of men on testosterone therapy. Those data did not show increased clotting, strokes, or heart attacks tied to testosterone. Because of that evidence, the FDA removed the specific clot and heart attack language from its black box warning earlier in the year.
That update matters. For years, clinicians had to warn patients about clot risk because of an official warning on drug labels. The new data and the FDA change make it easier to have honest conversations based on current science rather than old assumptions.
How Testosterone Affects Clotting
Nico describes testosterone and its metabolite dihydrotestosterone as having anti-coagulation effects. In simple terms, healthy androgen levels support factors that reduce clot formation and help blood move through vessels. This matches what clinicians see in real life. Younger men with higher testosterone rarely have clots. As testosterone drops with age, clotting and cardiovascular risks rise. The pattern suggests low testosterone is associated with higher clot risk rather than testosterone causing clots.
What About Genetic Clotting Risks Like Factor V Leiden?
Nico clarifies this common concern. People with inherited clotting disorders, such as Factor V Leiden, are at a higher baseline risk for clots. Giving testosterone does not appear to further increase that risk. In other words, testosterone therapy is not the factor that creates the high risk. The genetic condition already raises baseline risk. Most large trials did not screen every participant for every rare clotting disorder, so many people with those conditions were likely included. Still, the studies did not show a rising clot risk from the therapy itself.
Why Doctors Still Warn Against TRT
Nico explains two big reasons the myth persists. First, many cardiologists trained under older data and remain cautious. Cardiology focuses on preventing heart events and clots, so practitioners often advise against anything perceived as risky. Second, surgeons commonly ask patients to stop hormone therapy before operations out of fear of clots. Both groups are trying to protect patients. However, the fear is often rooted in outdated information rather than current evidence.
Why Stopping Testosterone Before Surgery Can Do Harm
Stopping testosterone in the days or weeks around surgery can lower a patient’s anabolic and anti-inflammatory protection. Testosterone supports healing, tissue repair, and healthy inflammatory balance. Nico argues that taking someone off therapy before or after surgery may slow recovery, increase infections, and reduce healing. He points to historical case reports and older examples where topical testosterone helped tough wounds heal. Those examples show the hormone can aid recovery rather than harm it.
Practical Advice For Patients and Clinicians
- Be informed. Read the major trials, such as the Traverse trial, and follow updated FDA guidance.
- Talk with your team. If a cardiologist or surgeon advises stopping therapy, discuss the evidence calmly and ask for the data behind their recommendation.
- Consider the risk context. A patient with Factor V Leiden has a higher baseline risk. That does not mean testosterone causes additional risk, but it does mean a tailored plan is needed.
- Think about continuity of care. Abruptly stopping hormone therapy around surgery can remove the body’s natural support for healing.
Why This Matters
Nico emphasizes that old myths lead to poor care. If patients are taken off therapy needlessly, they may lose the benefits that support weight loss, mood, libido, muscle mass, and cardiovascular health. Clinicians should aim to protect patients using up-to-date evidence, not outdated warnings. When providers and patients use the best available data, outcomes improve.
Where To Learn More
Nico teaches deeper on this topic in his HRT University master course for clinicians. He also writes a FREE Daily Newsletter with practical ideas about hormone therapy, medicine, and business!
FAQ
Q: Does testosterone replacement therapy cause blood clots?
A: No. Large clinical trials, including the Traverse trial, show no increased risk of venous thromboembolism directly caused by testosterone replacement therapy. The FDA removed clot and heart attack language from the black box warning after reviewing this evidence.
Q: What if a patient has Factor V Leiden or another clotting disorder?
A: People with genetic clotting disorders have a higher baseline risk for clots. Current evidence does not show testosterone therapy increases that risk further. Each case should be assessed individually and managed with careful clinical judgment.
Q: Should patients stop testosterone before surgery?
A: Automatic stopping is not supported by the evidence. Stopping therapy can remove anabolic and anti-inflammatory benefits that aid healing. Discuss risks and benefits with the surgical team and consider current literature before making a decision.
Q: Why do some doctors still warn against TRT?
A: Many clinicians learned older data that suggested harms. Specialties such as cardiology and surgery are cautious by nature. Updating practice to match recent trials takes time and education. Patients and providers should share current evidence to guide decisions.
Q: Where can clinicians learn more about safe TRT practice?
A: Clinicians can review the Traverse trial and recent FDA notes. Programs like HRTUniversity.com and focused master courses offer structured training on hormone replacement therapy and how to apply evidence in practice.
Final ThoughtsNico expects the conversation to shift as more clinicians read the data. He encourages both providers and patients to ask for evidence rather than rely on habit. For daily insights and clear, practical guidance on hormone therapy and medicine, sign up for Nico’s FREE Daily Newsletter! It is a short email every weekday designed to cut through the noise and help you care smarter.
For a complete overview of hormone replacement and bioidentical hormone therapy, see BHRT vs HRT: A Clinical Guide for Prescribing Clinicians.
